This invention relates to an anti-backlash nut and more particularly to a linear positioning device where precise repeatability and accuracy is required. Specifically, the present invention encompasses elimination of backlash between a lead screw and mating nut through the use of a preload force applied by a spring through the nut mechanism.
Present devices reduce backlash at the expense of increasing the frictional drag within the assembly. Other devices use axial loading to bring portions of the nut into contact with portions of the screw thread face while another part of the nut contacts the opposite thread face to make up for variations in lead screw thread variations and system wear. Some previous available designs use torsional springs, a large number of component parts, and/or an axially split nut thread.
Illustrations of anti-backlash nut assemblies utilizing axially split nuts are illustrated in U.S. Pat. Nos. 4,131,031 and Re. 31,713. U.S. Pat. No. 2,690,682 illustrates another type of anti-backlash nut which utilizes a pin and socket to prevent rotational movement between a pair of nut segments.